Time spent at sheltered anchorage can extend maximum underwater hours by what percent?

• A. 25%
• B. 50%
• C. 75%
• D. 100%

Answer: (B)

The key idea is that how long you can stay underwater is set by the amount of breathing gas you have and how quickly you use it. In a sheltered anchorage, conditions are calmer and you’re exerting less effort. That means your breathing rate and air consumption drop, so your gas lasts longer. Typically, this calmer state can extend maximum underwater hours by about 50% — you’re using gas more slowly, so you can remain submerged longer than in rougher, more demanding conditions. For example, if you could stay underwater for about two hours in open seas, you might expect roughly three hours at a sheltered anchorage. Of course, actual results depend on depth, temperature, gear, and your fitness, but the standard takeaway is that calmer conditions commonly yield a 50% increase in allowable underwater time.